The air network can be broadly divided into two categories- Low Altitude Platform (LAP) and High Altitude Platform (HAP). The LAP operates within an altitude of a few kilometres and the HAP generally operates
in the stratosphere. The HAP has longer endurance and wider coverage capabilities but the HAP overlaps with LEO
satellite networks [1]}, [2]}. On the other hand, LAP uses low frequency, Millimeter-wave (mmWave) bands, and microwaves for providing flexible and reliable connectivity by dense employment of flying base stations (BSs) and UAVs. The UAVs can act as relay nodes for long distance communications, and thus promote the integration of space and terrestrial networks. But the most interesting and helpful characteristic of UAVs is that it can facilitate mobile communications in areas where adequate infrastructures are absent [3]}. The UAVs have high speed mobility, and therefore, more advanced mobile network protocols are required for UAVs. The adaptive hybrid communication has potential and surpasses the existing protocols [4]}. A fully integrated 6G network can be expected to have multilayer architectures including UAV based LAPs, LEO satellites, GEO satellites, and heterogeneous terrestrial networks [1]}, [6]}, [7]}.
